Hi Troels,
I've completed the SBA MTM-16. Many thanks as always for your ongoing
inspiration, output, emails, and contribution to the DIY community!
Here's my review on these great sounding speakers. Enclosed are
building/testing photos.

SBA MTM-16:

INTRODUCTION:
For years, I've used the D'Appolito based Adam S3A as nearfield monitors
for my piano recordings. I recently built the Ellam D'Appo and now SBA
MTM-16. Joseph D'Appolito studied and designed speakers locally in the
Boston area. D'Appolitos present a nearfield image at farfield
distances. It's like listening to monitors at a distance. This imaging
offers great immediacy when the speakers are pointed at you in the
horizontal plane. They have wide horizontal and narrow vertical
dispersion characteristics. However, when listening outside the
horizontal plane or "sweet spot," you lose the magical immediacy and
near field directness. D'Appolitos sound great in wide (versus narrow)
rooms, and the vertical null zone is also effective in minimizing
ceiling, or floor reflections.

CONSTRUCTION:
Instead of floorstanders, these speakers were made to sit atop a stereo
pair of Scan-Speak 32W subs. Maintaining front baffle width, the height
was decreased, and the depth was increased to yield 40L. The cabinet
measures 29.5in x 9in x 15in. Instead of 20mm Baltic birch, 25mm was
used on the sides and back, and 38mm black MDF for the front baffle for
a strong enclosure. Bevelling the edges maintained a 8.5in baffle width.
Vibration damping sheets, felt, and 30mm acoustilux were used as
directed. Jantzen kit components were used. The crossover is accessible
via the removable bottom panel. The Baltic birch cabinet was finished
with GelStain. Lacquer toner spray brought out the color saturation,
contrast, and detail in the wood. The front panel was sprayed with black
primer and lacquer. The entire cabinet was finished with 6 coats of
polyurethane. The build took 65 hours.

Based on nearly identical parameters, I thought the Be tweeter could be
a "drop in replacement" for the standard TW29 tweeter. So when the MTM
first appeared with a standard tweeter, I asked Jantzen to substitute a
Be tweeter instead of 'more of the same' standard tweeter. They put my
order on hold to first ask you (blame me for the extra work;). I really
wanted to hear this much anticipated Be tweeter. I kept the 2.2 and 2.7
R on the crossover for versatility. Indeed, the 2.7 Ohm has a flatter
response with the Be version.

SOUND:
After 20 hours of break-in, it was only fitting to compare the SBA MTM
16 with the Ellam D'Appo. I've been very impressed with the Ellam
D'Appos. The 15W mid has exemplary clarity, smoothness, detail,
and potent bass. Surprisingly, the 5.5in Ellam D'Appo delivers more bass
at half the volume than the 6.5in SBA MTM. The 15Ws move more air than
MW16Ps at the port. The price is efficiency, as the Ellam D'Appo is 4dB
less efficient than the SBA MTM-16s. As for the midrange, the light cone
weight of the MW16P produces faster transients and more transparency
compared to the heavier coned Scan-Speak 18W and 18WU midwoofers in my
other speakers. The lack of compression in the mids at high volume is
also impressive. The treble is where the MTM's higher sensitivity
renders tremendous inner detail with more clarity, texture, and dynamics
over the Ellam D'Appo. The Be tweeter offers more accuity, timbral
definition, air, and blacker background without smear or veiling of
detail in highs. Overall, the soundstage is open, airy, spacious.

Like voicing instruments, I tend to voice speakers with different caps
for based on analog/digital sources, sold-state/tube amplification, ICs,
and genre of music. These new Alumen Z Caps render coherence and
transparency, without sacrificing detail nor dynamics. The Alumen Z Caps
have more "analog" warmth than Rike S-Caps or Mundorfs that I've used.
Regarding the crossover, the MTM's presence in the 700-1000Hz region
makes most music engaging. However, on some piano recordings too much
timbral highlights lead to some stridency on solid state amps. Perhaps
the LCR would've been a nice switchable option. However, this didn't
occur on tube amps.

CONCLUSION:
The SBA 16MTM produces a neutral, coherent, detailed, dynamic, open,
airy, spacious sound. These speakers are equally suited for analog or
digital sources, and solid state or tube gear. The high efficiency makes
them ideal for my KT88 push-pull amp as the difference can be heard. The
SBA 16 MTM is an uprade from the Ellam D'Appo offering greater
transparency, detail, dynamics, and holographic imaging. The SBA MTM
excels in textural and timbral information. These observations were made
without the subwoofers. The MTM can stand alone without subs, however,
in a large room, subs offer extension below 40Hz. In the pipeline are
the MUN17, ATS-4, and Scan-Speak Ophelia speakers.